Effects of ingesting a sports bar versus glucose polymer on substrate utilisation and ultra-endurance performance

The purpose of this study was to determine whether the ingestion of a sport s bar (BAR) containing a mixture of fat (7 g), protein (14g) and carbohydra te (CHO; 19g) improved ulta-endurance cycling performance compared to when an equicaloric amount of CHO was consumed. On two occasions separated by a minimum of 7 days, six highly trained (peak power output [PPO] 414+/-8W) en durance cyclists rode for 330 min at similar to 50% of PPO (203 +/- 8 W) wh ile ingesting either the BAR or just CHO, before performing a 400 kj time t rial as fast as possible. Rates of fat oxidation were significantly greater at the end of the submaximal ride when subjects ingested the BAR compared to CHO (1.09 +/- 0.08 vs 0.73 +/- 0.08 g min(-1); P < 0.05), and accordingl y total fat oxidation was significantly higher (280+/-24 vs 203 +/- 25 g, P < 0.05). However, two subjects failed to complete the time trial after they consumed the BAR during the prolonged, submaximal ride; whereas all subjec ts managed to finish the time trial when ingesting CHO. In conclusion, inge stion of the sports bar enhanced fat metabolism during prolonged, submaxima l exercise, but impaired subsequent high-intensity time-trial performance.